Hello all, first time poster here. My daily driver is a 1991 745 with the Regina fuel management system, AW70L trans. and 250k. For the past year or so the car has exhibited a lumpy, low idle while in gear warm or cold. Since the symptoms first began, I suspected the IAC valve as other likely culprits had been addressed. Over the course of the past year, I had installed three different used Regina IAC valves on the car, with the last one being "shiny new" pulled from a recently totaled salvage yard car. The "shiny new" valve was only marginally better than the previous valves.

Out of curiosity, I spliced in a used two prong Bosch valve, pulled from a 2.4lh car. An old Bosch fuel injector connector and pigtail replaced the wider Regina connector for the valve. (Both Regina and Bosch valves pin out essentially the same at the fuel ecu).

Problem solved. The car idles smoothly while in gear, (@ 750ish according to tach in instrument cluster). I have little doubt that a new Regina valve would have fixed the problem as well, for considerably more $! For what it's worth, the Bosch valve measured 34 degrees of dwell compared to the "shiny new" Regina's 29 degrees on my old (and questionable) dwell meter.

I'll try to make future posts less lengthy! Hope this can help someone.